We propose a study of the reactions of the airborne pollutants; ozone, nitrogen dioxide, and cigarette smoke with lipids and biological membranes. All these materials contain free radicals and/or initiate oxidation reactions in polyunsaturated fatty acids (PUFA), lipids and membranes, and it is likely that radicals and these autoxidation reactions play a key role in the biological damage produced by these toxic pollutants. Nevertheless, there has been very little study of the chemistry of these important pathological processes. We plan to examine substrates of increasing complexity and biological relevance in our studies, beginning with simple esters of PUFA, aqueous emulsions of PUFA esters, and finally synthetic models of membranes (liposomes). We will study the products and the mechanisms of the reactions of ozone and N02 in low concentrations with PUFA esters and lipids and the nature of the inhibition by biologically important free radical inhibitors such as alpha-tocopherol and GSH. We will utilize electron spin resonance (esr) and the spin trap method to attempt to detect, identify, and measure the concentrations of free radicals in the gas phase of cigarette smoke, in cigarette smoke condensates, and in whole smoke.